The present invention relates to an exchange system of which the signal transfer is based on a two-wire bidirectional burst transfer system.
With recent remarkable progress of digital signal processing technology, there has been developed and put into practice an exchange system in which a digital transfer of signal is performed between an exhange and various types of terminal devices. Of the digital transfer systems, the two-wire bidirectional burst transfer system, a called ping-pong transfer system, has attracted a great attention because of the following two advantageous features. The digital transfer allows the existing analog two-way telephone lines to be available, as they are intact, for the concurrent transfer of voice and data. It is relatively easy to take a synchronization in the signal transfer. If employing this type of the transfer system for exchange system configuration, an advanced exchange system can easily be realized by connecting to an exchange not only standard telephone exchanges but also various types of data terminal devices capable of the concurrent transfer of voice and data. In the exchange system using such terminal devices, it is necessary to previously set in a memory of an exchange the information representating what types of terminal devices are respectively connected to interface circuits or subscriber's circuits, by using a maintenance program, for example. For this reason, it was needed to change the set information every time the terminal device is changed from one to another. To cope with frequent situations where the exchange must concurrently handle both voice and data, an approach assigns two time slots to each of the interface circuits, one for voice exchange and the other for data exchange. According to this approach, the two time slots are assigned to even the terminal devices handling only voice or data. In this case, either of the two time slots is void in use, resulting in deterioration of the transfer efficiency of voice and data.